液化空气储能基本循环的热力学分析

目的   以新能源为主体的新型电力系统对储能的需求不断增加，液化空气储能是一种新兴的长时间、大容量物理储能方法，具有广泛的应用前景。文章旨在探究液化空气储能的热力学原理以及关键参数对储能效率的影响规律。 方法   建立了液化空气储能三种基本循环：分离式循环、冷能回收循环、冷能热能回收循环的热力学模型，分析了冷能回收、热能回收、高压压力、释能压力等关键参数对液化率和循环效率的影响。 结果   结果表明液化率与循环效率正相关。分离式循环的液化率与循环效率极低，冷能回收循环由于利用了液空复温过程中的冷量可以显著提升液化率与循环效率，冷能热能回收循环在此基础上利用了压缩热而进一步提升液化率与循环效率。液化率与循环效率随冷能回收量的增加而升高、随高压压力的升高而升高、随释能压力的升高而下降。 结论   冷能热能回收循环是液化空气储能的优选方案。高效蓄冷将对提升循环效率发挥重要作用。在液空复温过程中利用工业余热、废热有助于进一步提升循环效率。

Thermodynamic Analysis of Basic Cycles of Liquid Air Energy Storage System

  Introduction  The demand for energy storage of new power systems (dominated by renewable energy) is increasing. Liquid air energy storage is a new method of physical energy storage with large capacity for long time storage, which has a broad application prospect. the purpose is to explore the thermodynamic principle of liquid air energy storage system and the influence of key parameters on energy storage efficiency.   Method  The thermodynamic models of three basic cycles of liquid air energy storage system: separated cycle, cooling capacity recovery cycle and cooling capacity and heat recovery cycle were established. The influence of key parameters such as cold energy recovery, heat recovery, high pressure and discharge pressure on liquid yield and cycle efficiency was analyzed.   Result  The results show that there is a positive correlation between liquid yield and cycle efficiency. The liquid yield and cycle efficiency of the separated cycle are extremely low. The cooling capacity recovery cycle, using the cooling capacity during temperature rise, significantly improves the liquid yield and cycle efficiency. The cooling capacity and heat recovery cycle further improve the liquid yield and recycling efficiency for the use of heat of compression. The liquid yield and cycle efficiency increase with the increase of cooling capacity recovery, increase with the increase of high pressure, and decrease with the increase of discharge pressure.   Conclusion  Cooling capacity and heat recovery cycle is the optimal scheme of liquid air energy storage. Efficient cooling capacity storage plays an important role in improving cycle efficiency. The utilization of industrial waste heat in the process of liquid-air reheating is helpful to further improve cycle efficiency.